Design and synthesis of ammonia-modified reduced graphene oxide possessing more amino groups for methylene blue adsorption

Abstract

To obtain a high-performance functional graphene with more amino groups, chlorine-functionalized reduced graphene oxide (RGO) reacts with ammonia. The N content of the product is high, which means that bonds of C and Cl react with ammonia. The interlayer distance is larger than that of RGO. The product has a higher adsorption capacity (170.1 mg g⁻¹) for methylene blue than activated carbon (46.7 mg g⁻¹) and RGO (77.0 mg g⁻¹). The product can be regenerated and reused six times with slight changes in adsorption capacities; thus, it might be useful for practical applications. The adsorption data are consistent with the quasi second-order kinetics and the Langmuir model. In addition, the adsorption capacity (164.2 mg g⁻¹) of the product for Cr(III) is higher than that (73.2 mg g⁻¹) of RGO.